Urinary tract infections (UTI) remain among the most common bacterial infections. They are a frequent cause of morbidity and constitute a large public health cost to society. Recurrent UTIs constitute a serious health problem, especially to adult women and female children. These infections are caused primarily by E. coli which infect the bladder by an ascending route from the fecal flora. Even in patients without demonstrable vesicoureteral reflux or obstruction, a lower tract UTI may proceed to pyelonephritis. The overall goal of this research is to establish a safe, effective vaccine treatment against UTI. Inception of a UTI is a process that requires specific interactions between virulent bacteria and a susceptible patient. One of the most important of these interactions is the adherence of uropathogenic bacteria to epithelial cells lining the vagina, urethra, and bladder. Antibody directed against adhesions on pathogenic E. coli will interfere with this adherence. Consequently, we have developed animal models to test whether immunization with an E. coli vaccine would decrease the incidence or duration of an induced UTI. Results from our studies in rodents and non-human primates have shown that a vaginal mucosal immunization regimen enhances both urinary and serum anti-E. coli Ab responses and shortens the time needed to resolve a cystitis. Some untreated monkeys develop protracted infections and some animals remain susceptible after immunization. This increased susceptibility appears to be linked to an inability of some animals to produce antibody to antigens associated with uropathogenic strains of E. coli. Whether a similar situation of selective immunologic hyporesponsiveness (congenital or acquired) could explain UTI susceptibility in patients remains to be determined. In this proposal we will: 1) conduct clinical trials of a multi-strain, killed whole-cell vaccine, 2) correlate UTI susceptibility with deficiencies in UTI protective antibodies in women with recurrent UTI and experimental animals, and 3) develop an accellular, endotoxin-free E. coli vaccine against UTI.